Display device

ABSTRACT

According to one embodiment, a display device includes a first substrate, a second substrate and a liquid crystal layer. The first substrate includes a base, a sensor and a sensor circuit. The sensor is interposed between the base and the liquid crystal layer in a display area including pixels. The sensor outputs a sensing signal corresponding to light incident from alongside the liquid crystal layer. The sensor circuit includes a plurality of switching elements. The pixels include first to third sub-pixels. At least some of elements of the switching elements are arranged in each of areas where the first to third sub-pixels are arranged. A signal line for the sensor, which outputs the sensing signal, is placed on a same layer as a feeding line connected to the sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2021-047327, filed Mar. 22, 2021, theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a display device.

BACKGROUND

In recent years, a display device having a built-in sensor that detectsbiological information, such as a fingerprint sensor and a vein sensor,has been developed. As this type of sensor, for example, an opticalsensor using a photoelectric conversion element is used.

The optical sensor is provided in a pixel in the display device.Accordingly, the aperture ratio of the pixel is lowered and thus thedisplay device is likely to decrease in its display quality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a display device according to anembodiment.

FIG. 2 is a schematic plan view of the display device according to theembodiment.

FIG. 3 is an equivalent circuit diagram showing an example of aconfiguration of a pixel according to the embodiment.

FIG. 4 is a schematic sectional view showing an example of a structureapplicable to a first substrate according to the embodiment.

FIG. 5 is a schematic plan view showing an example of a structureapplicable to the first substrate according to the embodiment.

FIG. 6 is a schematic plan view showing an example of a structureapplicable to the first substrate according to the embodiment.

FIG. 7 is a schematic plan view showing an example of a structureapplicable to the first substrate according to the embodiment.

FIG. 8 is a schematic plan view showing an example of a structureapplicable to the first substrate according to the embodiment.

FIG. 9 is a schematic sectional view showing a structure of a firstsubstrate according to a comparative example.

FIG. 10 is an equivalent circuit diagram showing an example of aconfiguration of a sensor circuit for a sensor according to theembodiment.

FIG. 11 is a schematic plan view showing a structure of the firstsubstrate to which the sensor circuit of FIG. 10 is applied.

FIG. 12 is a schematic plan view showing a structure of the firstsubstrate to which the sensor circuit of FIG. 10 is applied.

DETAILED DESCRIPTION

In general, according to one embodiment, a display device includes afirst substrate, a second substrate and a liquid crystal layer. Thesecond substrate is opposed to the first substrate. The liquid crystallayer is interposed between the first substrate and the secondsubstrate. The first substrate includes a base, a sensor and a sensorcircuit. The sensor is interposed between the base and the liquidcrystal layer in a display area including pixels. The sensor outputs asensing signal corresponding to light incident from alongside the liquidcrystal layer. The sensor circuit includes a plurality of switchingelements. The sensor circuit is connected to the sensor. The pixelsinclude a first sub-pixel emitting light of a first color, a secondsub-pixel emitting light of a second color and a third sub-pixelemitting light of a third color. At least some of elements of theswitching elements are arranged in each of areas where the firstsub-pixel, the second sub-pixel and the third sub-pixel are arranged. Asignal line for the sensor, which outputs the sensing signal from thesensor, is placed on a same layer as a feeding line connected to thesensor.

Embodiments will be described hereinafter with reference to theaccompanying drawings.

Note that the disclosure is merely an example, and proper changes withinthe spirit of the invention, which are easily conceivable by a skilledperson, are included in the scope of the invention as a matter ofcourse. In addition, in some cases, in order to make the descriptionclearer, the widths, thicknesses, shapes, etc., of the respective partsare schematically illustrated in the drawings, compared to the actualmodes. However, the schematic illustration is merely an example, andadds no restrictions to the interpretation of the invention. Besides, inthe specification and drawings, the same or similar elements as or tothose described in connection with preceding drawings or thoseexhibiting similar functions are denoted by like reference numerals, anda detailed description thereof is omitted unless otherwise necessary.

Further, in order to make the descriptions more easily understandable,some of the drawings illustrate an X axis, a Y axis and a Z axisorthogonal to each other. A direction along the X axis is referred to asan X direction or a first direction, a direction along the Y axis isreferred to as a Y direction or a second direction and direction alongthe Z axis is referred to as a Z direction or a third direction. A planedefined by the X axis and the Y axis is referred to as an X-Y plane, anda plane defined by the X axis and the Z axis is referred to as an X-Zplane. Further, viewing towards the X-Y plane is referred to as planarview.

FIG. 1 is a schematic diagram showing a display device DSP according toan embodiment. The display device DSP includes a display panel PNL, acover member CM, a first polarizer PLZ1, a second polarizer PLZ2 and anillumination device BL.

The display panel PNL is a liquid crystal display panel and includes afirst substrate SUB1, a second substrate SUB2 opposed to the firstsubstrate SUB1, a sealing member SE and a liquid crystal layer LC. Theliquid crystal layer LC is sealed between the first and secondsubstrates SUB1 and SUB2 by the sealing member SE. The display panel PNLof the present embodiment is of a transmission type in which an image isdisplayed by selectively transmitting light from the back surface sideof the first substrate SUB1 to the upper surface side of the secondsubstrate SUB2.

The first substrate SUB1 includes a sensor SS and a light-shieldinglayer SLS for the sensor. The sensor SS is interposed between the liquidcrystal layer LC and the light-shielding layer SLS. Although not shownin FIG. 1, a collimating layer may also be interposed between the sensorSS and the liquid crystal layer LC. The collimating layer is alight-shielding layer and has an opening. Although not shown in FIG. 1,a collimating layer may be formed on the second substrate SUB2.

By the sealing member SE, the first and second substrates SUB1 and SUB2are bonded to each other. Between the first and second substrates SUB1and SUB2, a prescribed cell gap is formed by a spacer (not shown). Theliquid crystal layer LC is filled in the cell gap.

The cover member CM is provided on the display panel PNL. For example, aglass substrate and a resin substrate can be used as the cover memberCM. The cover member CM has an upper surface USF in contact with atarget object to be detected by the sensor SS. In the example of FIG. 1,a finger F as an example of the target object is in contact with theupper surface USF. The first polarizer PLZ1 is provided between thedisplay panel PNL1 and the cover member CM.

The illumination device BL is provided under the display panel PNL toirradiates the first substrate SUB1 with light L. The illuminationdevice BL is, for example, a side-edge backlight, and includes aplate-shaped light guide and a plurality of light sources that emitlight onto the side surfaces of the light guide. The second polarizerPLZ2 is provided between the display panel PNL and the illuminationdevice BL.

Of the light L, light reflected by finger F enters the sensor SS.Specifically, the reflected light is transmitted through the covermember CM, first polarizer PLZ1, second substrate SUB2, liquid crystallayer LC, and a portion of the first substrate SUB1 which is locatedabove the sensor SS.

The sensor SS outputs a sensing signal corresponding to the incidentlight. As will be described later, the display panel PNL includes aplurality of sensors SS. In response to the sensing signals of thesensors SS, the surface (for example, a fingerprint) of finger F can bedetected.

The sensors SS preferably sense incident light parallel to the normaldirection of the upper surface USF in order to obtain a more accuratesensing signal. When the foregoing collimating layers are formed on thefirst and second substrates SUB1 and SUB2, they can function ascollimators that collimate light incident upon the sensors SS.

If the display device DSP is mounted with the sensors SS as describedabove, it can have a function of a fingerprint sensor. In addition, thesensors SS can be used to detect information on a living body based onlight reflected inside finger F in addition to or instead of detecting afingerprint. The information on a living body is, for example, an imageof a blood vessel such as a vein, a pulse, a pulse wave, and the like.

FIG. 2 is a schematic plan view of the display device DSP according tothe present embodiment. The display device DSP includes the foregoingdisplay panel PNL and a wiring substrate 1 mounted on the display panelPNL. The display panel PNL includes a display area DA for displaying animage and a surrounding area SA surrounding the display area DA. Thesurrounding area SA may be referred to as a non-display area.

The first substrate SUB1 includes a mounting area MA which does notoverlap the second substrate SUB2. The sealing member SE is located inthe surrounding area SA. In FIG. 2, an area where the sealing member SEis placed is indicated by hatching. The display area DA is locatedinside the sealing member SE. The display panel PNL includes a pluralityof pixels PX which are arranged in a matrix in the first and seconddirections X and Y in the display area DA.

The pixels PX each include a sub-pixel SP1 emitting red (R) light, asub-pixel SP2 emitting green (G) light, and a sub-pixel SP3 emittingblue (B) light. Note that the pixels PX may include sub-pixels emittinglight other than red, green and blue light.

In the example of FIG. 2, one sensor SS is provided for each of thepixels PX. In the entire display area DA, a plurality of sensors SS arearranged in a matrix in the first and second directions X and Y.

The sensor SS need not be located for all the pixels PX. For example,one sensor SS may be provided for a plurality of pixels PX. Further,sensors SS may be provided for the pixels PX in part of the display areaDA and may not always be provided for the pixels PX in the other partthereof.

The wiring substrate 1 is, for example, a flexible circuit board, and isconnected to a terminal portion that is provided in the mounting areaMA. The wiring substrate 1 also includes a driver 2 that drives thedisplay panel PNL. Note that the driver 2 may be mounted in another areasuch as the mounting area MA. For example, the driver 2 includes an ICthat controls a display operation of each of the pixels PX and an ICthat controls a sensing operation of the sensors SS. These ICs may bemounted at different locations. The sensors SS output sensing signals toa controller CT via the wiring substrate 1 and the driver 2. In responseto the sensing signals from the sensors SS, the controller CT executesan arithmetic operation and the like to detect a fingerprint.

FIG. 3 is an equivalent circuit diagram showing an example of aconfiguration of sub-pixels SP1, SP2 and SP3 included in the pixel PXaccording to the present embodiment. The sub-pixels SP1, SP2 and SP3 arearranged in their respective areas partitioned by scanning lines GLextending along the first direction X and arranged along the seconddirection Y and signal lines SLR, SLG and SLB extending along the seconddirection Y and arranged along the first direction X. The scanning linesGL may be referred to as pixel scanning lines, and the signal lines SLR,SLG and SLB may be referred to as pixel signal lines. In the following,when a signal line of a specific color is not suggested, the signal linemay simply be referred to as a signal line SL. Similarly, in thefollowing, when a sub-pixel of a specific color is not suggested, thesub-pixel may simply be referred to as a sub-pixel SP.

The sub-pixels SP1, SP2 and SP3 each include a switching element SW1. Inthe switching element SW1, a gate electrode is connected to a scanningline GL, a source electrode is connected to signal lines SLR, SLG andSLB of corresponding colors, and a drain electrode is connected to oneof the electrodes of a capacitor Cst. The other electrode of thecapacitor Cst is connected to a feeding line PL. The feeding line PL maybe referred to as a pixel feeding line.

Sensor circuits are placed mainly in the area including the sub-pixelSP3 that emits blue light, and are connected to the sensors SS to drivethe sensors SS. As elements related to the sensors SS, a first scanningline SGL1 for the sensor, a second scanning line SGL2 for the sensor, afirst feeding line SPL1 for the sensor, a second feeding line SPL2 forthe sensor, a third feeding line SPL3 for the sensor and a signal lineSSL for the sensor are provided.

Hereinafter, the first scanning line SGL1 will be referred to as a firstscanning line SGL1, the second scanning line SGL2 will be referred to asa second scanning line SGL2, the first feeding line SPL1 will bereferred to as a first feeding line SPL1, the second feeding line SPL2will be referred to as a second feeding line SPL2, and the third feedingline SPL3 will be referred to as a third feeding line SPL3.

The first and second scanning lines SGL1 and SGL2 extend along the firstdirection X and are arranged along the second direction Y. As will bedescribed later in detail, the first feeding line SPL1 is superposed onthe signal line SLR in planar view, the second and third feeding linesSPL2 and SPL3 are superposed on the signal line SLG in planar view, andthe signal line SSL is superposed on the signal line SLB in planar view.

The sensor circuits for sensors SS each include a switching element SW2,a switching element SW3 and a switching element SW4. In FIG. 3, theswitching elements SW2, SW3 and SW4 are each configured by an n-typethin film transistor (TFT); however, they may be configured by a p-typeTFT.

In each of the sensors SS, one electrode is connected to second feedingline SPL2 and the other electrode is connected to a node N. The node Nis connected to the drain electrode of the switching element SW2 and thegate electrode of the switching element SW3. The second feeding lineSPL2 applies a second voltage (VCOM) is applied to one electrode of thesensor SS. The second voltage may be referred to as a reference voltage.When light enters the sensor SS, capacitance is formed between theelectrodes of the sensor SS.

In the switching element SW2, the gate electrode is connected to thefirst scanning line SGL1, the source electrode is connected to the firstfeeding line SPL1, and the drain electrode is connected to the node N.When the switching element SW2 is turned on in response to a scanningsignal supplied from the first scanning line SGL1, the potential of thenode N is reset to the potential of a first voltage (VPP1) applied fromthe first feeding line SPL1. The second voltage is lower than the firstvoltage, and the sensor SS is driven by reverse bias.

In the switching element SW3, the gate electrode is connected to thenode N, the source electrode is connected to the third feeding lineSPL3, and the drain electrode is connected to the source electrode ofthe switching element SW4. When the switching element SW3 is turned onby the above-described capacitance formed in the sensor SS, it outputs asensing signal corresponding to the capacitance to the switching elementSW4.

In the switching element SW4, the gate electrode is connected to thesecond scanning line SGL2, the source electrode is connected to thedrain electrode of the switching element SW3, and the drain electrode isconnected to the signal line SSL. When the switching element SW4 isturned on in response to a scanning signal supplied from the secondscanning line SGL2, the switching element SW3 outputs the sensing signalto the signal line SSL.

In addition to the sensors SS, touch detection lines TL1 and TL3 aresuperposed on the signal lines SLR and SLB in planar view in order todetect whether an external object (for example, finger F) is close to orin contact with the display area DA.

Although FIG. 3 shows a case where the switching elements SW2 and SW4have a double-gate structure, they may have a single-gate structure or amulti-gate structure.

A structure applicable to the first substrate SUB1 will be described inmore detail with reference to FIGS. 4 to 8. FIGS. 4 to 8 are schematicsectional and plan views each showing a configuration of the firstsubstrate SUB1. The locations or shapes of the elements in these figuresare not necessarily the same.

FIG. 4 is a schematic sectional view showing an example of a structureapplicable to the first substrate SUB1. The first substrate SUB1includes a transparent first base 10, insulating layers 11 to 19 and analignment film AL.

The first base 10 is, for example, a glass substrate and a resinsubstrate. The insulating layers 11 to 14, 16 and 19 are formed of aninorganic material. The insulating layers 15, 17 and 18 are formed of anorganic material. The insulating layers 11 to 19 and the alignment filmAL are stacked above the first base 10 in the third direction Z in thatorder described.

The first substrate SUB1 includes, as elements related to image display,a signal line SL, a scanning line GL, a switching element SW1, a pixelelectrode PE, a common electrode CE, relay electrodes R1 to R5 and afeeding line PL. The pixel electrode PE and the switching element SW1are provided for each of the sub-pixels SP1, SP2 and SP3. The commonelectrode CE is provided over the sub-pixels SP1, SP2 and SP3, forexample.

The switching element SW1 includes a semiconductor layer SC1. Thesemiconductor layer SC1 is formed between the insulating layers 11 and12. The scanning line GL is formed between the insulating layers 12 and13 and opposed to the semiconductor layer SC1. Note that the scanningline GL may be formed in another layer, not between the insulatinglayers 12 and 13. The signal line SL is formed between the insulatinglayers 14 and 15, and is in contact with the semiconductor layer SC1through a contact hole CH1 that penetrates the insulating layers 12, 13and 14.

In the example of FIG. 4, a light-shielding layer LS is formed betweenthe first base 10 and the insulating layer 11. At least a part of thesemiconductor layer SC1, which is opposed to the scanning line GL, isalso opposed to the light-shielding layer LS.

The relay electrode R1 is interposed between the insulating layers 14and 15, and is in contact with the semiconductor layer SC1 through acontact hole CH2 that penetrates the insulating layers 12, 13 and 14.The relay electrode R2 is interposed between the insulating layers 15and 16, and is in contact with the relay electrode R1 through a contacthole CH3 that penetrates the insulating layer 15. The relay electrode R3is interposed between the insulating layers 16 and 17, and is in contactwith the relay electrode R2 through a contact hole CH4 that penetratesthe insulating layer 16. The relay electrode R4 is interposed betweenthe insulating layers 17 and 18, and is in contact with the relayelectrode R3 through a contact hole CH5 that penetrates the insulatinglayer 17. The relay electrode R5 is interposed between the insulatinglayers 18 and 19, and is in contact with the relay electrode R4 througha contact hole CH6 that penetrates the insulating layer 18.

The pixel electrode PE is interposed between the insulating layer 19 andthe alignment film AL, and is in contact with the relay electrode R5through a contact hole CH7 that penetrates the insulating layer 19. Thefeeding line PL is interposed between the insulating layers 17 and 18.The common electrode CE is interposed between the insulating layers 18and 19, and is in contact with the feeding line PL through a contacthole CH8 that penetrates the insulating layer 18.

A common voltage is applied to the feeding line PL. The common voltageis also applied to the common electrode CE. The signal line SL issupplied with a video signal, and the scanning line GL is supplied witha scanning signal. When the scanning line GL is supplied with a scanningsignal, the pixel electrode PE is supplied with a video signal from thesignal line SL through the semiconductor layer SC1 and the relayelectrodes R1 to R5. At this time, an electric field is generatedbetween the pixel electrode PE and the common electrode CE by adifference in potential between the common voltage and the video signal,and this electric field acts on the liquid crystal layer LC.

The first substrate SUB1 includes, as elements related to the sensorsSS, a switching element SW2, a first scanning line SGL1, relayelectrodes R6 to R8, a first feeding line SPL1, a switching element SW3,a gate electrode GE, a second feeding line SPL2, a switching elementSW4, a second scanning line SGL2, relay electrodes R9 to R13, a thirdfeeding line SPL3, and a signal line SSL for the sensor, in addition tothe light-shielding layer SLS for the sensor. The sensor SS includes afirst electrode E1 (lower electrode), a second electrode E2 (upperelectrode), and a photoelectric conversion element PC.

The light-shielding layer SLS includes a first light-shielding layerSLS1 and a second light-shielding layer SLS2. The switching element SW2includes a semiconductor layer SC2. The semiconductor layer SC2 isformed between the insulating layers 11 and 12. The first scanning lineSGL1 is interposed between the insulating layers 12 and 13 and opposedto the semiconductor layer SC2. Note that the first scanning line SGL1may be formed in another layer, not between the insulating layers 12 and13.

In the example of FIG. 4, the first light-shielding layer SLS1 isinterposed between the first base 10 and the insulating layer 11. Atleast a part of the semiconductor layer SC2, which is opposed to thefirst scanning line SGL1, is also opposed to the first light-shieldinglayer SLS1.

The relay electrode R6 is interposed between the insulating layers 14and 15, and is in contact with the semiconductor layer SC2 through acontact hole CH9 that penetrates the insulating layers 12, 13 and 14.The relay electrode R7 is interposed between the insulating layers 14and 15, and is in contact with the semiconductor layer SC2 through acontact hole CH 10 that penetrates the insulating layers 12, 13 and 14.The relay electrode R8 is interposed between the insulating layers 15and 16, and is in contact with the relay electrode R7 through a contacthole CH11 that penetrates through the insulating layer 15.

The first feeding line SPL1 is interposed between the insulating layers16 and 17 and is in contact with the relay electrode R8 through acontact hole CH 12 that penetrates the insulating layer 16. A firstvoltage (VPP1) is applied to the first feeding line SPL1.

The switching element SW3 includes a semiconductor layer SC3. Thesemiconductor layer SC3 is interposed between the insulating layers 11and 12. The gate electrode GE is interposed between the insulatinglayers 12 and 13 and opposed to the semiconductor layer SC3. The gateelectrode GE is in contact with the relay electrode R6 through a contacthole CH13 that penetrates the insulating layers 13 and 14.

The photoelectric conversion element PC has a first surface F1 opposedto the first base 10 and a second surface F2 opposed to the liquidcrystal layer LC. The photoelectric conversion element PC is locatedbetween the insulating layers 15 and 16. The first electrode E1 isinterposed between the photoelectric conversion element PC and theinsulating layer 15 and is in contact with the first surface F1. Theouter periphery of the first electrode E1 protrudes from thephotoelectric conversion element PC and is covered with an insulatinglayer 16. The first electrode E1 is in contact with the relay electrodeR6 through a contact hole CH 14 that penetrates the insulating layer 15below the photoelectric conversion element PC. The second electrode E2is interposed between the photoelectric conversion element PC and theinsulating layer 16 and is in contact with the second surface F2. Thesecond electrode E2 is in contact with the second feeding line SPL2through a contact hole CH15 that penetrates the insulating layer 16above the photoelectric conversion element PC.

The second feeding line SPL2 is interposed between the insulating layers16 and 17, and is in contact with the second electrode E2 through acontact hole CH15 that penetrates the insulating layer 16. A secondvoltage (VCOM) is applied to the second feeding line SPL2.

The switching element SW4 includes a semiconductor layer SC3. That is,the semiconductor layer SC3 is shared by the switching elements SW3 andSW4. The second scanning line SGL2 is interposed between the insulatinglayers 12 and 13 and opposed to the semiconductor layer SC3, and doesnot overlap the gate electrode GE. Note that the second scanning lineSGL2 may be formed in another layer, not between the insulating layers12 and 13.

In the example of FIG. 4, the second light-shielding layer SLS2 isformed between the first base 10 and the insulating layer 11. At least apart of the semiconductor layer SC3, which is opposed to the gateelectrode GE and the second scanning line SGL2, is also opposed to thesecond light-shielding layer SLS2.

The relay electrode R9 is interposed between the insulating layers 14and 15, and is in contact with the semiconductor layer SC3 through acontact hole CH16 that penetrates the insulating layers 12, 13 and 14.The relay electrode R10 is interposed between the insulating layers 15and 16, and is in contact with the relay electrode R9 through a contacthole CH17 that penetrates the insulating layer 15. The relay electrodeR11 is interposed between the insulating layers 16 and 17, and is incontact with the relay electrode R10 through a contact hole CH18 thatpenetrates the insulating layer 16.

The third feeding line SPL3 is formed between the insulating layers 17and 18, and is in contact with the relay electrode R11 through a contacthole CH19 that penetrates the insulating layer 17. A third voltage(VPP2) is applied to the third feeding line SPL3.

The relay electrode R12 is interposed between the insulating layers 14and 15, and is in contact with the semiconductor layer SC3 through acontact hole CH20 that penetrates the insulating layers 12, 13 and 14.The relay electrode R13 is interposed between the insulating layers 15and 16, and is in contact with the relay electrode R12 through a contacthole CH21 that penetrates the insulating layer 15.

The signal line SSL for the sensor is formed between the insulatinglayers 16 and 17, and is in contact with the relay electrode R13 througha contact hole CH22 that penetrates the insulating layer 16.

The light-shielding layers LS and SLS are formed of the same metalmaterial. The signal lines SL and relay electrodes R1, R6, R7, R9 andR12 are formed of the same metal material. The first electrode E1 andrelay electrodes R2, R8, R10 and R13 are formed of the same metalmaterial. The first feeding line SPL1, second feeding line SPL2, signalline SSL and relay electrodes R3 and R11 are formed of the same metalmaterial. The feeding line PL, third feeding line SPL3 and relayelectrode R4 are formed of the same metal material. The second electrodeE2, pixel electrode PE, common electrode CE and relay electrode R5 areformed of a transparent conductive material such as indium tin oxide(ITO).

The first electrode E1, which is formed of a metal material, alsofunctions as a light-shielding layer to suppress light incident frombelow onto the photoelectric conversion element PC. The photoelectricconversion element PC is, for example, a photodiode, and outputs anelectrical signal (sensing signal) corresponding to incident light. Morespecifically, a positive intrinsic negative (PIN) photodiode can be usedas the photoelectric conversion element PC. This type of photodiodeincludes a p-type semiconductor layer, an i-type semiconductor layer andan n-type semiconductor layer. The p-type semiconductor layer is locatedalongside the second electrode E2, the n-type semiconductor layer islocated alongside the first electrode E1, and the i-type semiconductorlayer is located between the p-type and n-type semiconductor layers.

The p-type semiconductor layer, i-type semiconductor layer and n-typesemiconductor layer are formed of, for example, amorphous silicon(a-Si). Note that the material of the semiconductor layers is notlimited to the amorphous silicon, but the amorphous silicon may bereplaced with polycrystalline silicon, microcrystalline silicon, and thelike, and the polycrystalline silicon may be replaced with amorphoussilicon, microcrystalline silicon, and the like.

The first and second scanning lines SGL1 and SGL2 are each supplied witha scanning signal with timing of sensing by the sensor SS. When thefirst and second scanning lines SGL1 and SGL2 are supplied with ascanning signal, they output to the signal line SSL a sensing signal tobe generated by the photoelectric conversion element PC. The sensingsignal output to the signal line SSL is supplied to the controller CTvia the driver 2, for example.

FIG. 5 is a schematic plan view showing elements applicable to the firstsubstrate SUB1 and interposed between the insulating layers 12 and 15shown in FIG. 4. In FIG. 5, contact holes for contacting elements belowthe signal lines SL are indicated by broken lines, and contact holes forcontacting elements above the signal lines SL are indicated by solidlines.

The scanning lines GL, first scanning line SGL1 and second scanning lineSGL2 extend along the first direction X and are arranged along thesecond direction Y. The first and second scanning lines SGL1 and SGL2are arranged adjacent to each other in the second direction Y. The firstand second scanning lines SGL1 and SGL2 are interposed between adjacenttwo scanning lines GL. The signal lines SL extend along the seconddirection Y and are arranged along the first direction X.

The sub-pixels SP1, SP2 and SP3 are arranged in an area surrounded byadjacent two scanning lines GL arranged along the second direction Y andadjacent two signal lines SL arranged along the first direction X. Thesub-pixels SP1, SP2 and SP3 have their respective openings surrounded bythe second scanning line SGL2, the first scanning line SGL1 and theadjacent two signal lines SL.

The first scanning line SGL1 has a branch portion (protruding portion)extending along the second direction Y. The branch portion functions asa gate electrode of the switching element SW2. The semiconductor layerSC2 is formed in an area superposed on the gate electrode of theswitching element SW2 in planar view.

The semiconductor layer SC2 is formed across the opening of thesub-pixel SP3 and the opening of the sub-pixel SP1, and overlaps thesignal line SLB corresponding to the sub-pixel SP3. An island-shapedrelay electrode R7 is placed in the opening of the sub-pixel SP1 tooverlap the semiconductor layer SC2. The relay electrode R7 is incontact with the semiconductor layer SC2 through the contact hole CH10.The relay electrode R7 is also in contact with a relay electrode placedabove the relay electrode R7 through the contact hole CH11. Anisland-shaped relay electrode R6 is placed in the opening of thesub-pixel SP3 to overlap the semiconductor layer SC2. The relayelectrode R6 is in contact with the semiconductor layer SC2 through thecontact hole CH9.

The relay electrode R6 is in contact with the gate electrode GE of theswitching element SW3 through the contact hole CH13. The gate electrodeGE of the switching element SW3 is placed in the opening of thesub-pixel SP3 to overlap the relay electrode R6 in planar view. Notethat the relay electrode R6 is in contact with the first electrode E1,which is placed above the relay electrode R6, through the contact holeCH14.

The second scanning line SGL2 has a branch portion (protruding portion)extending along the second direction Y. The branch portion functions asa gate electrode of the switching element SW4. The semiconductor layerSC3 is formed in an area superposed on the gate electrode of theswitching element SW4 in planar view.

The semiconductor layer SC3 is formed across the opening of thesub-pixel SP2, the opening of the sub-pixel SP3 and the opening of thesub-pixel SP1, and overlaps the signal line SLG corresponding to thesub-pixel SP2 and the signal line SLB corresponding to the sub-pixelSP3. An island-shaped relay electrode R9 is placed in an opening of thesub-pixel SP2 to overlap the semiconductor layer SC3. The relayelectrode R9 is in contact with the semiconductor layer SC3 through thecontact hole CH16. The relay electrode R9 is also in contact with arelay electrode placed above the relay electrode R9 through the contacthole CH17.

An island-shaped relay electrode R12 is placed in an opening of thesub-pixel SP1 to overlap the semiconductor layer SC3. The relayelectrode R12 is in contact with the semiconductor layer SC3 through thecontact hole CH20. The relay electrode R12 is also in contact with arelay electrode placed above the relay electrode R12 through the contacthole CH21.

The switching element SW1 is interposed between the first scanning lineSGL1 and the scanning line GL as an element related to image display.The semiconductor layer SC1 included in the switching element SW1 is incontact with the signal line SL of the corresponding color through thecontact hole CH1.

FIG. 6 is a schematic plan view showing elements applicable to the firstsubstrate SUB1 and interposed between the insulating layers 16 and 17shown in FIG. 4. In FIG. 6, contact holes for contacting elements belowthe first feeding line SPL1, second feeding line SPL2 and signal lineSSL are indicated by broken lines, and contact holes for contactingelements above the first feeding line SPL1, second feeding line SPL2 andsignal line SSL are indicated by solid lines. FIG. 6 also shows thepixel scanning line GL, pixel signal line SL, the first scanning lineSGL1 and second scanning line SGL2 shown in FIG. 5, in order to make therelationship in location among the elements easier to understand.

The first electrode E1 of the sensor SS is placed in the opening of thesub-pixel SP3. The first electrode E1 is in contact with the lower relayelectrode R6 through the contact hole CH14. The photoelectric conversionelement PC is placed on the first electrode E1. The second electrode E2of the sensor SS is placed on the photoelectric conversion element PC.The second electrode E2 is in contact with the second feeding line SPL2through the contact hole CH15. The second feeding line SPL2 extendsalong the second direction Y so as to be superposed on the signal lineSLG corresponding to the sub-pixel SP2 in planar view. The secondfeeding line SPL2 has a branch portion (protruding portion) extendingalong the first direction X, and is in contact with the second electrodeE2 at the branch portion. Accordingly, the second feeding line SPL2 andthe sensor SS are electrically connected to each other to allow thesecond voltage (VCOM) to be applied to the sensor SS.

An island-shaped relay electrode R10 is placed in the opening of thesub-pixel SP2. The relay electrode R10 is in contact with the lowerrelay electrode R9 through the contact hole CH17. The relay electrodeR10 is in contact with a relay electrode R11 placed above the relayelectrode R10 through a contact hole CH18. The relay electrode R11 isplaced in the opening of the sub-pixel SP2 and superposed on the relayelectrode R10 in planar view, and is in contact with the lower relayelectrode R10 through the contact hole CH18. The relay electrode R11 isin contact with the third feeding line SPL3, which is placed above therelay electrode R11, through the contact hole CH19.

An island-shaped relay electrode R13 is placed in the opening of thesub-pixel SP1. The relay electrode R13 is in contact with the lowerrelay electrode R12 through the contact hole CH21. The relay electrodeR13 is in contact with the signal line SSL, which is placed above therelay electrode R13, through the contact hole CH22. The signal line SSLextends along the second direction Y so as to be superposed on thesignal line SLB corresponding to the sub-pixel SP3 in planar view. Thesignal line SSL has a branch portion (protruding portion) extendingalong the first direction X, and is in contact with the relay electrodeR13 at the branch portion.

An island relay electrode R8 is placed in the opening of the sub-pixelSP1. The relay electrode R8 is in contact with the lower relay electrodeR7 through the contact hole CH11. The relay electrode R8 is in contactwith the first feeding line SPL1, which is placed above the relayelectrode R8, through the contact hole CH12. The first feeding line SPL1extends along the second direction Y so as to be superposed on thesignal line SLR corresponding to the sub-pixel SP1 in planar view. Thefirst feeding line SPL1 has a branch portion (protruding portion)extending along the first direction X, and is in contact with the relayelectrode R8 at the branch portion. Accordingly, the first feeding lineSPL1 and the switching element SW2 are electrically connected to eachother to allow the first voltage (VPP1) to be applied to the switchingelement SW2.

FIG. 7 is a schematic plan view showing elements applicable to the firstsubstrate SUB1 and interposed between the insulating layers 17 and 18shown in FIG. 4. FIG. 7 also shows the pixel scanning line GL, pixelsignal line SL, first scanning line SGL1 and second scanning line SGL2shown in FIG. 5 in order to make the relationship in location among theelements easier to understand.

The third feeding line SPL3 has a branch portion (protruding portion)extending along the second direction Y so as to be superposed on thesignal line SLG corresponding to the sub-pixel SP2 in planar view. Atthe branch portion, the third feeding line SPL3 is in contact with therelay electrode R11, which is placed in the opening of the sub-pixelSP2, through the contact hole CH19. Accordingly, the third feeding lineSPL3 and the switching element SW3 are electrically connected to eachother to allow the third voltage (VPP2) to be applied to the switchingelement SW3.

FIG. 8 is a schematic plan view showing elements applicable to the firstsubstrate SUB1 in order to describe the relationship in location betweenthe pixel electrode PE and the sensor circuit for the sensor SS.

The pixel electrodes PE of the sub-pixels SP1, SP2 and SP3 have the sameshape. Each of the pixel electrodes PE is placed in an area surroundedby two scanning lines GL and two signal lines SL. In the example of FIG.8, the pixel electrode PE has three line portions LP extending along thesecond direction Y and arranged along the first direction X. Theopenings of the sub-pixels SP1, SP2 and SP3 overlap their respectiveline portions LP of the sub-pixels SP1, SP2 and SP3.

Each of the pixel electrodes PE is at least partly superposed onelements (switching elements SW2, SW3 SW4) constituting the sensorcircuit for the sensor SS in planar view. For example, the pixelelectrode PE of the sub-pixel SP2 is superposed on the semiconductorlayer SC3, relay electrode R9 and the like in planar view. The pixelelectrode PE of the sub-pixel SP3 is superposed on the semiconductorlayer SC2, relay electrode R6, gate electrode GE, semiconductor layerSC3, branch portion of the second scanning line SGL2, and the like inplanar view. The pixel electrode PE of the sub-pixel SP1 is superposedon the semiconductor layer SC2, relay electrode R7, branch portion ofthe first scanning line SGL1, semiconductor layer SC3, relay electrodeR12, and the like in planar view. Note that the pixel electrode PE ofthe sub-pixel SP3 is superposed on the photoelectric conversion elementsPC constituting the sensor SS in planar view.

According to the present embodiment described above, the sensor SSplaced in the display area DA makes it possible to provide a displaydevice DSP capable of detecting the surface unevenness of finger F thatis in contact with or close to the display area DA.

In the present embodiment, the elements included in the sensor circuitfor the sensor SS are distributed to their respective sub-pixels SP1,SP2 and SP3. It is thus possible, for example, to balance the apertureratios of the sub-pixels SP1, SP2 and SP3 in comparison with the casewhere the elements are arranged only in one sub-pixel SP. That is, ifthe elements included in the sensor circuit for the sensor SS arearranged only in one sub-pixel SP, the aperture ratio of the onesub-pixel SP becomes extremely lower than that of the other twosub-pixels SP, with the result that the display quality may be degraded.According to the configuration of the present embodiment, the apertureratios of the sub-pixels SP1, SP2 and SP3 can be balanced and thus thedisplay quality can be prevented from being degraded.

In the present embodiment, the elements included in the sensor circuitfor the sensor SS are distributed to the sub-pixels SP1, SP2 and SP3 byarranging some of the switching elements SW2 in the sub-pixel SP1emitting red light, arranging some of the switching elements SW3 and SW4in the sub-pixel SP2 emitting green light, and arranging the remainingelements in the sub-pixel SP3 emitting blue light. However, it may bedetermined in consideration of the influence of the aperture ratios ofthe sub-pixels SP1, SP2 and SP3 upon the display quality how theelements included in the sensor circuit for the sensor SS aredistributed.

In addition to the above, various favorable advantages can be obtainedfrom this embodiment. Further advantages of the present embodiment willbe described with reference to the comparative example shown in FIG. 9.Note that the comparative example is intended to described some of theadvantages that can be achieved by the present embodiment, and theadvantages common to the comparative example and the present embodimentare not excluded from the scope of the present invention.

The configuration of the comparative example differs from that of thepresent embodiment shown in FIG. 4 in that the signal line SSL for thesensor is interposed between the insulating layers 13 and 14. It alsodiffers from that of the present embodiment shown in FIG. 4 in that arelay electrode R′ is interposed between the insulating layers 13 and14.

In the configuration of the comparative example, the relay electrode R′and relay electrode R6 are opposed to each other with the insulatinglayer 14 formed of an inorganic material therebetween, and thuscapacitance is formed between the relay electrodes R′ and R6. Thiscapacitance is added as parasitic capacitance to capacitance formedbetween the first and second electrodes E1 and E2 of the sensor SS.Since this parasitic capacitance affects the detection accuracy of thesurface unevenness of finger F by the sensor SS, it is preferable thatthe parasitic capacitance is smaller.

In the configuration of the present embodiment, no electrodecorresponding to the relay electrode R′ of the comparative example isplaced because the signal line SSL for the sensor is interposed betweenthe insulating layers 16 and 17. The parasitic capacitance in thepresent embodiment can be made smaller than that in the comparativeexample.

In the configuration of the comparative example, furthermore, the signalline SSL is interposed between the insulating layers 13 and 14, and thusit is covered with the insulating layer 14 formed of an inorganicmaterial. An insulating layer formed of an inorganic material is morelikely to cause a step due to wiring than an insulating layer formed ofan organic material (it is more difficult to cover a step due towiring).

In the configuration of the present embodiment, the signal line SSL islocated between the insulating layers 16 and 17 and above the insulatinglayer 15 formed of an organic material, and is covered with theinsulating layer 17 formed of an organic material. Thus, the influenceof a step due to the signal line SSL can be made smaller than that inthe comparative example.

In addition, when a first substrate SUB1 is formed in the configurationof the comparative example, a step of forming a contact hole penetratingthe insulating layers 12 and 13 and a step of forming the signal lineSSL and the relay electrode R′ between the insulating layers 13 and 14are required, but when a first substrate SUB1 is formed in theconfiguration of the present embodiment, the signal line SSL can beformed in the same step as the step of forming the relay electrode R3and the second feeding line SPL2; thus, the above two steps can beomitted. That is, the configuration of the present embodiment makes itpossible to form the first substrate SUB1 with a smaller number of stepsthan the configuration of the comparative example.

Here is a brief description of a series of steps for forming the firstsubstrate SUB1 in configuration of the present embodiment.

First, a light-shielding layer LS and a light-shielding layer SLS for asensor are formed on the first base 10. Then, semiconductor layers SC1,SC2 and SC3 are formed on the insulating layer 11 which covers thelight-shielding layers LS and SLS. A light doped drain region is formedin the semiconductor layers SC1, SC2 and SC3 by ion implantation. Ascanning line GL, a first scanning line SGL1, a second scanning lineSGL2 and a gate electrode GE are formed on the insulating layer 12 whichcovers the semiconductor layers SC1, SC2 and SC3. With the scanning lineGL, first scanning line SGL1, second scanning line SGL2 and gateelectrode GE as masks, the semiconductor layers SC1, SC2 and SC3 aredoped with impurities to form a p+ region.

After the insulating layers 13 and 14 are formed, contact holes CH1,CH2, CH9, CH10, CH16 and CH20 penetrating the insulating layers 12, 13and 14 are formed, and a contact hole CH13 penetrating the insulatinglayers 13 and 14 is formed. A signal line SL and relay electrodes R1,R6, R7, R9 and R12 are formed on the insulating layer 14. After theinsulating layer 15 is formed, contact holes CH3, CH11, CH14, CH17 andCH21 penetrating the insulating layer 15 are formed. Relay electrodesR2, R8, R10, R13 and a first electrode E1 are formed on the insulatinglayer 15. A photoelectric conversion element PC is formed on the firstelectrode E1. The insulating layer 15 formed of an organic material hasa flattening function, and the first electrode E1 and the photoelectricconversion element PC are formed on the flattened insulating layer 15. Asecond electrode E2 is formed on the photoelectric conversion elementPC. After the insulating layer 16 is formed, contact holes CH4, CH12,CH15, CH18 and CH22 penetrating the insulating layer 16 are formed.Relay electrodes R3 and R11, a first feeding line SPL1, a second feedingline SPL2 and a signal line SSL for the sensor are formed on theinsulating layer 16.

After the insulating layer 17 is formed, contact holes CH5 and CH 19penetrating the insulating layer 17 are formed. A feeding line PL, arelay electrode R4 and a third feeding line SPL3 are formed on theinsulating layer 17. After the insulating layer 18 is formed, contactholes CH6 and CH8 penetrating the insulating layer 18 are formed. Arelay electrode R5 and a common electrode CE are formed on theinsulating layer 18. After the insulating layer 19 is formed, a contacthole CH7 penetrating the insulating layer 19 is formed. Thereafter, apixel electrode PE is formed on the insulating layer 19, and analignment film AL covering the pixel electrode PE is formed.

Various modifications can be made to the foregoing configurationdisclosed in the present embodiment. In the present embodiment, thesensor circuit for the sensor SS is configured to include threeswitching elements SW2, SW3 and SW4, but the present invention is notlimited to this configuration. The sensor circuit for the sensor SS maybe configured to include two switching elements SW. Below is adescription of a configuration in which the sensor circuit for thesensor SS includes two switching elements SW.

FIG. 10 is an equivalent circuit diagram showing an example of aconfiguration of the sensor circuit for the sensor SS included in thepixel PX according to the present embodiment. Below are descriptions ofcomponents included in the sensor circuit and the relationship inconnection between the components.

The sensor circuit for the sensor SS includes a capacitor C1, acapacitor C2, a switching element SW2′ and a switching element SW3′.

One electrode of the sensor SS is connected to a second feeding lineSPL2 and the other electrode is connected to a node N′. The node N′ isconnected to one electrode of each of the capacitors C1 and C2, thesource electrode of the switching element SW2′ and the gate electrode ofthe switching element SW3′. The capacitor C1 holds capacitance that isformed between both the electrodes of the sensor SS according to theincidence of light. Capacitance held in the capacitor C2 is parasiticcapacitance added to the capacitance held in the capacitor C1.

The gate electrode of the switching element SW2′ is connected to a firstscanning line SGL1, the source electrode thereof is connected to thenode N′ and the drain electrode thereof is connected to a signal lineSSL for the sensor. The gate electrode of the switching element SW3′ isconnected to the node N′, the source electrode thereof is connected to athird feeding line SPL3 and the drain electrode thereof is connected tothe signal line SSL.

In FIG. 10, the switching elements SW2′ and SW3′ have a double-gatestructure. They may have a single-gate structure or a multi-gatestructure.

FIG. 11 is a schematic plan view showing a configuration of the firstsubstrate SUB1 to which the sensor circuit of FIG. 10 is applied.

The scanning lines GL, first scanning line SGL1 and second scanning lineSGL2 extend along the first direction X and are arranged along thesecond direction Y. The first and second scanning lines SGL1 and SGL2are arranged adjacent to each other in the second direction Y. The firstand second scanning lines SGL1 and SGL2 are interposed between adjacenttwo scanning lines GL. The signal lines SL extend along the seconddirection Y and are arranged along the first direction X.

The sub-pixels SP1, SP2 and SP3 are arranged in an area surrounded bytwo scanning lines GL arranged adjacent to each other along the seconddirection Y and two signal lines SL arranged adjacent to each otheralong the first direction X. The sub-pixels SP1, SP2 and SP3 each havean opening surrounded by the first and second scanning lines SGL1 andSGL2 and adjacent two signal lines SL.

The first scanning line SGL1 has a branch portion (protruding portion)extending along the second direction Y. The branch portion functions asa gate electrode of the switching element SW2′. A semiconductor layerSC2′ is formed in an area superposed on the gate electrode of theswitching element SW2′ in planar view. The second scanning line SGL2 hasa branch portion (protruding portion) extending along the seconddirection Y. The branch portion is superposed on the semiconductor layerSC2′ in planar view to form a capacitor C2.

The semiconductor layer SC2′ of the switching element SW2′ is providedacross the opening of the sub-pixel SP3 and the opening of the sub-pixelSP1, and overlaps the signal line SLB corresponding to the sub-pixelSP3.

An island-shaped relay electrode R30 is placed in the opening of thesub-pixel SP1 to overlap the semiconductor layer SC2′. The relayelectrode R30 is in contact with the semiconductor layer SC2′ throughthe contact hole CH30. An island-shaped relay electrode R31 is placed inthe opening of the sub-pixel SP3 to overlap the semiconductor layerSC2′. The relay electrode R31 is in contact with the semiconductor layerSC2′ through the contact hole CH31.

The relay electrode R31 is connected to the gate electrode GE′ of theswitching element SW3′ through the contact hole CH32. The gate electrodeGE′ of the switching element SW3′ is placed in the opening of thesub-pixel SP3, and stacked on the relay electrode R31 in planar view andoverlapped with the signal line SLG corresponding to the sub-pixel SP2.

The semiconductor layer SC3′ of the switching element SW3′ is providedacross the opening of the sub-pixel SP2 and the opening of the sub-pixelSP3, and overlaps the signal line SLG corresponding to the sub-pixelSP2. An island-shaped relay electrode R32 is placed in the opening ofthe sub-pixel SP2 to overlap the semiconductor layer SC3′. The relayelectrode R32 is in contact with the semiconductor layer SC3′ throughthe contact hole CH33.

An island-shaped relay electrode R33 is placed in the opening of thesub-pixel SP3 to overlap the semiconductor layer SC3′. The relayelectrode R33 is in contact with the semiconductor layer SC3′ throughthe contact hole CH34.

FIG. 12 is a schematic plan view showing a configuration of the firstsubstrate SUB1 to which the sensor circuit of FIG. 10 is applied inorder to describe the positional relationship between the pixelelectrode PE and the sensor circuit for the sensor SS.

The pixel electrodes PE of the sub-pixels SP1, SP2 and SP3 have the sameshape. Each of the pixel electrodes PE is placed in an area surroundedby two scanning lines GL and two signal lines SL. In the example of FIG.12, the pixel electrode PE has three line portions LP extending alongthe second direction Y and arranged along the first direction X. Theopenings of the sub-pixels SP1, SP2 and SP3 overlap the line portions LPof the sub-pixels SP1, SP2 and SP3, respectively.

Each of the pixel electrodes PE at least overlaps elements (switchingelements SW2′ and SW3′) constituting a sensor circuit for the sensor SSin planar view. For example, the pixel electrode PE of the sub-pixel SP2is superposed on the semiconductor layer SC3′, relay electrode R32 andthe like in planar view. The pixel electrode PE of the sub-pixel SP3 issuperposed on the semiconductor layer SC2′, relay electrode R31, gateelectrode GE′, semiconductor layer SC3′, relay electrode R33 and thelike in planar view. The pixel electrode PE of the sub-pixel SP1 issuperposed on the semiconductor layer SC2′, relay electrode R30, branchportion of the first scanning line SGL1 and the like in planar view.Note that the pixel electrode PE of the sub-pixel SP3 is superposed onthe photoelectric conversion element PC of the sensor SS in planar view.

As described above, even though the sensor circuit for the sensor SS isconfigured to include two switching elements SW2′ and SW3′, the sameadvantages as those in the case where the three switching elements SW2,SW3 and SW4 are distributed can be obtained because the switchingelements are distributed to each of the sub-pixels SP1, SP2 and SP3.That is, the display quality can be prevented from decreasing.

The embodiment described above makes it possible to provide a displaydevice capable of distributing the elements of the sensor circuit forthe sensor SS to each of the sub-pixels SP1, SP2 and SP3 and preventingdisplay quality from being lowered by incorporating the sensor SS(optical sensor).

In the present embodiment, the display device DSP is defined as a liquidcrystal display device including an illumination device BL. The displaydevice DSP is not limited thereto, but may be an organicelectroluminescent display device including an organic light-emittingdiode (OLED) as a display element.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A display device comprising: a first substrate; asecond substrate opposed to the first substrate; and a liquid crystallayer interposed between the first substrate and the second substrate,wherein: the first substrate includes: a base, a sensor interposedbetween the base and the liquid crystal layer in a display areaincluding pixels to output a sensing signal corresponding to lightincident from alongside the liquid crystal layer, and a sensor circuitincluding a plurality of switching elements and connected to the sensor;the pixels include a first sub-pixel emitting light of a first color, asecond sub-pixel emitting light of a second color and a third sub-pixelemitting light of a third color; at least some of elements of theswitching elements are arranged in each of areas where the firstsub-pixel, the second sub-pixel and the third sub-pixel are arranged;and a signal line for the sensor, which outputs the sensing signal fromthe sensor, is placed on a same layer as a feeding line connected to thesensor.
 2. The display device of claim 1, wherein: the sensor includes:a photoelectric conversion element having a first surface opposed to thebase and a second surface opposed to the liquid crystal layer, a firstelectrode that is in contact with the first surface, and a secondelectrode that is in contact with the second surface; and the secondelectrode is connected to the feeding line.
 3. The display device ofclaim 2, wherein: the first electrode is formed of a metal material; andthe second electrode is formed of a transparent conductive material. 4.The display device of claim 1, wherein the sensor signal line is coveredwith an insulating layer formed of an organic material.
 5. The displaydevice of claim 1, wherein: the first color is red; the second color isgreen; the third color is blue; and the sensor is placed in an areawhere the third sub-pixel is placed.